The world’s first calendar may be an eagle bone with rows of 14 or 15 notches made 30,000 years ago and found at Le Placard on the Dordogne River near Le Eyzies, France. The bone contains 69 mysterious marks and notches, including circles, crescents, arc and ear-shapes, that appear to be in synch with the phases of the moon. Fourteen and 15 days are roughly the interval between a new moon and a full moon. Some have suggested it may have helped women keep track of the menstrual cycle. Others say it may have been tabulating device Skeptic say it may just be a bone with a lot of scratches on it.
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